The present invention relates in general to reverse cycle type refrigeration systems, and more particularly to an economizer cycle piping and control arrangement for reverse cycle type refrigeration systems using a water cooled condenser.
In years past, most refrigeration systems were designed to operate at fixed standard design conditions year-round in the interest of standardizing on a fixed set of operating conditions so as to minimize the need for adjusting the settings on the various system components. For example, such designs based on fixed standard design conditions were intended to avoid having to adjust the settings on such components as the expansion valves, hand throttling valves, and the various other control and adjusting devices as well as fixed orifice devices so as to compensate for changes in pressure differentials that might exist if changes in condensing pressure would occur.
More recently, as the cost of electrical power has escalated in the amount of potential saving that could be realized by operating larger refrigeration systems at reduced condensing pressures when ambient conditions would allow it came to the attention of management, the "economizer cycle" for industrial refrigeration systems was developed and has become standard in the industry. The normal type of "economizer cycle" would not allow most reverse cycle type refrigeration systems to function satisfactorily, however, because of the wide range in condensing temperatures and pressures which are encountered as well as the great variation in heat available in the discharge gas over the range of operating conditions of the refrigeration system. Many intricate and complicated systems of controls have been designed in an attempt to solve these type problems for the various types of reverse cycle applications, but in most cases at least as many problems have been created as were solved by such designs.
The incorporation of an "economizer cycle" in an ice harvesting type of thermal storage refrigeration system is particularly desirable because ice harvesting type refrigeration system applications are particularly "cost-conscious" and must be justified in most cases by a relatively quick pay-back.
An object of the present invention, therefore, is the provision of a reverse cycle type refrigeration system having a water cooled condenser, wherein controls and piping are arranged to take advantage of increased capacity and efficiency available at lower ambient conditions during the normal ice making portion of the cycle of the system and having novel valve control means causing the unit to always have a constant, standard defrost cycle operated under constant preset conditions regardless of water tower temperatures to achieve economizer cycle operation when the unit is put into the harvest mode.
Another object of the present invention is the provision of a novel piping and control arrangement for reverse cycle type refrigeration systems as described in the immediately preceding paragraph, wherein cooling tower fans are set to operate at full capacity to deliver the coldest water possible down to a predetermined temperature whenever the tower pump runs and circulate a full flow of this cooling tower water through the condenser to operate at the lowest condensing pressure and highest efficiency and reduce power cost, during the ice making cycle, but which provides programed control to cause condensing pressure to increase quickly up to a predetermined trip point to put the unit into the harvesting mode assuring operation of the defrost cycle under constant pre-set conditions regardless of tower water temperatures.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with accompanying drawing illustrating a preferred embodiment of the invention.